The present invention relates to a phosphor that is suitable for a light-emitting element excited by vacuum ultraviolet-ray, such as a plasma display panel (hereinafter, referred to as xe2x80x9cPDPxe2x80x9d) and a rare gas lamp, and also relates to a light-emitting element excited by vacuum ultraviolet-ray comprising the phosphor.
A phosphor has been used for elements excited by vacuum ultraviolet-ray such as PDP""s and rare gas lamps, and the phosphor which is excited by vacuum ultraviolet rays to emit light has already been known. For example, the following phosphors have been practically used: aluminate phosphors, such as BaMgAl10O17: Eu for use as a blue phosphor and BaAl12O19: Mn for use as a green phosphor (JP10-1666A); silicate phosphors, such as CaMgSi2O6: Eu for use as a blue phosphor and Zn2SiO4: Mn for use as a green phosphor; and borate phosphors, such as (Y, Gd) BO3: Eu for use as a red phosphor, and these materials have been used for light emitting element excited by vacuum ultraviolet-ray such as PDP""s and rare gas lamps.
Light emitting element emit visible light radiated from phosphor which is irradiated and excited by vacuum ultraviolet-ray radiated from the plasma, which is generated during the discharge of the light emitting element in a rare gas. Consequently, the phosphor is exposed by plasma to cause a reduction in the brightness of the phosphor after plasma exposure.
The objective of the present invention is to provide a phosphor for use in a light emitting element excited by vacuum ultraviolet-ray that has high brightness even after plasma exposure.
Under such circumstances, the inventors of the present invention have extensively studied in order to solve the above-mentioned problems, and found that, among aluminate phosphors containing Mn as an activating agent and gallium acid salt phosphors containing Mn as an activating agent, a phosphor obtained from an aluminate or a gallium acid salt having a specific composition has high brightness after plasma exposure, and is effectively used as a phosphor for use in a light emitting element excited by vacuum ultraviolet-ray, in particular, as a green light-emitting phosphor, and then, completed the present invention.
That is, the present invention provides a phosphor comprising a compound represented by a formula M11xe2x88x92aM211xe2x88x92bMna+bO18xe2x88x92(a+b)/2 (wherein, M1 represents at least one of materials selected from the group consisting of La, Y and Gd, and M2 represents at least one of materials selected from the group consisting of Al and Ga, a represents an number in a range from not less than 0 to less than 1, b represents a number in a range from not less than 0 to less than 1, and sum of a and b is greater than 0).
Moreover, the present invention also provides a light emitting element excited by vacuum ultraviolet-ray comprising the above-mentioned phosphor.